Gaia Data Release 3: Spectroscopic binary-star orbital solutions

The SB1 processing chain

¹ Institut d’Astrophysique et de Géophysique, Université de Liège, 19c, Allée du 6 Août, 4000 Liège, Belgium
² CRAAG-Centre de Recherche en Astronomie, Astrophysique et Géophysique, Route de l’Observatoire, Bp 63 Bouzareah, 16340 Algiers, Algeria
³ Université de Strasbourg, CNRS, Observatoire Astronomique de Strasbourg, UMR 7550, 11 rue de l’Université, 67000 Strasbourg, France
⁴ Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles CP 226, Boulevard du Triomphe, 1050 Brussels, Belgium
⁵ INAF – Osservatorio Astrofisico di Torino, via Osservatorio 20, 10025 Pino Torinese (TO), Italy
⁶ GEPI, Observatoire de Paris, Université PSL, CNRS, 5 Place Jules Janssen, 92190 Meudon, France

^★ Corresponding author; eric.gosset@uliege.be

Received: 3 May 2024
Accepted: 8 October 2024

Abstract

Context. The Gaia satellite constitutes one of ESA’s cornerstone missions. Being primarily an astrometric space experiment measuring positions, proper motions, and parallaxes for a huge number of stars, it also performs photometric and spectrophotometric observations. Gaia operates a medium-dispersion spectrometer, known as Radial Velocity Spectrometer (RVS), which provides spectra and radial velocity (RV) time series.

Aims. The paper is focussed on the analysis of the RV time series. We fit orbital and trend models, restricting our study to objects of spectral types F-G-K that are brighter than a magnitude of 12, presenting only one single spectrum (SB1).

Methods. Suitable time series were processed and analysed on an object-per-object basis, providing orbital or trend solutions. The results of the various fits were further filtered internally on the basis of several quality measures to discard spurious solutions. The objects with solely a spectroscopic solution were classified in one of the three classes: SB1 (eccentric model), SB1C (circular model), or TrendSB1 (mere trend model).

Results. We detail the methods used in this work and describe the derived parameters and results. After a description of the models considered and the related quality tests of the fit, we detail the internal filtering process aimed at rejecting bad solutions. We also present a full validation of the pipeline. A description of the current content of the catalogue is also provided.

Conclusions. We present the SB1, SB1C, and TrendSB1 spectroscopic solutions contained in the SB subcatalogue, part of the DR3 catalogue. We deliver some 181 327 orbital solutions in class SB1, 202 in class SB1C, and 56 808 in the associated class TrendSB1. This is a first release and the delivered SB subcatalogue could be further tuned and refined. However, the majority of the entries are correct. Thus, this data set constitutes by far the largest set of spectroscopic orbital solutions to be computed.